The drug -- herbs treated with chemicals designed to mimic the effects of marijuana -- ranked third next to alcohol and marijuana, which 57 percent and 39 percent of students in grades nine through 12 reported using, respectively. About 12 percent of students reported using synthetic marijuana, more than those who used cocaine, ecstasy and prescription pain relievers.

Eric Wish, director of CESAR, said that the federal government has had a hard time cracking down on the rapidly evolving drug. Last summer, President Barack Obama signed a ban on synthetic marijuana and bath salts, a synthetic drug that mimics the effects of cocaine.

As quickly as the chemicals used to make the drug is banned, new ones are created.

"It's a significant portion of young people, and we're just beginning to create a strategy to deal with this," Wish said. "And as marijuana becomes more and more openly used in our society for medicine, it's likely that kids will go ahead and buy something they think is marijuana, without realizing how dangerous these news substances can be."

So far, two new cannabinoids -- UR-144 and XLR-11 -- have emerged, Wish said.

"In reality," the report concluded, "youth who report using synthetic marijuana likely have no idea what specific synthetic cannabinoid they are using or what the effects will be."

Read The Sun's coverage on synthetic marijuana, and efforts to stop local sales, here.